The present invention relates to a device for transferring current between two contact points.
Between these two contact points there is arranged a ribbon cable which serves for the electric connection and is wound in turns concentric to each other in the manner of a spring housing, the cable having at least one electric conductor having its ends firmly attached to the two contact points, at least one of the two contact points being movable relative to the other along a path concentric to the turns of the ribbon cable, and the ends of the ribbon cable being folded so that they protrude at an angle of 90.degree. from the ribbon cable, the end regions of the ribbon cable which contain the folded places being embedded in an insulator which is produced by extrusion, and parts being provided on the ends of the ribbon cable around the axis of which said ends are swingable (Federal Republic of Germany GM 85 05 830).
Apparatus having such devices are, for instance, coilers in which an electric cable is wound on a bobbin. The cable can be pulled out of the housing of the apparatus and be automatically rewound under the action of a spring after the release of a pulling force. The apparatus can also be an anti-rebound device for automotive vehicles in which an electric current lead is arranged in the steering wheel of an automotive vehicle. One essential problem in such devices is the transfer of the current between the fixed contact and the movable contact. This problem arises in the case of all apparati in which two contact points which are movable relative to each other are present, one of which contact points is generally developed as a fixed point. The wiper contacts or wiper rings which have been known for a long time for such cases are subject to wear and are disadvantageous because of their high contact resistances, particularly in the case of low current intensities.
In the aforementioned known device in accordance with Federal Republic of Germany GM 85 05 830, the transfer of current is effected by a ribbon cable which is wound in the manner of a spring housing. Upon a relative rotary movement of the two contact points connected by the ribbon cable the wound ribbon cable expands like the spring of a clock. The turns are pulled in one direction of rotation into a small diameter. In the other direction of rotation they return to a large diameter. This known device has the disadvantage that an insulating member which surrounds the folded ends of the ribbon cable can be produced only at great expense since the light, flexible ribbon cable very easily moves out of its central position during injection molding. The insulating members then do not uniformly surround the ends of the ribbon cable. It can even easily occur that the ribbon cable is disengaged on one side of the insulating member. Such a ribbon cable would be a complete reject. Another disadvantage of this known device is that the part of the insulating member surrounding the free end of the ribbon cable serves at the same time for a pivotal mounting of the end of the ribbon cable. This part must therefore furthermore be produced with great dimensional accuracy and at correspondingly increased expense.
It is an object of the invention to provide a device for the transfer of current by means of a ribbon cable which is wound in the manner of a spring housing and in which assurance is obtained in simple fashion that the ends of the ribbon cable are embedded in each case in a predetermined position in an insulating member produced by injection molding.